One chemical reaction potentially useful as a curing reaction is Michael addition. For example, US Patent Application 20030083436 discloses a composition, useful as an adhesive, comprising a product of a reaction between an α,β-unsaturated multi-carboxylic acid ester and a particular polyester or polyamide compound with methylene groups adjacent to carbonyl groups, in the presence of a non-amine strong base catalyst such as an alkali alkoxide.
Use of strong base catalysts are well known for Michael addition reactions whereas the use of weak base catalysts for curing at 25° C. or lower is not known, as described by Clemens and Rector (Journal of Coatings Technology, Vol. 61, No. 770, 1989). U.S. Pat. No. 6,855,796 B2 discloses the use of tertiary phosphine weak bases to prepare oligomeric or low molecular weight polymeric, non-cross-linked curable resins which are further cured to high polymer by exposure to actinic radiation. These curable resins are prepared at elevated temperatures (50-90° C.). U.S. Pat. No. 6,855,796 B2, however, does not teach the use of the phosphine weak base catalysts to produce high polymer or cross-linked polymer and does not teach the use of weak bases to effect curing at ambient temperatures. Further, it does not teach the use of weak base catalysts to produce adhesives, including laminating adhesives, two-component or two-pack adhesives, sealants, foams, films or elastomers.
One drawback to previously known compositions is that some catalysts are undesirably toxic or corrosive. Another drawback to previously known compositions is that some catalysts are undesirably reactive with ubiquitous materials (like, for example, air and/or water) and/or with ingredients of the composition before cure and/or with products of the process of curing the composition. One example is the use of soluble strong base catalysts (pKa>11) that may lead to hydrolysis or otherwise degrade reactants or products. Another example is the use of amine bases that can cause discoloration or yellowing. It is desired to provide compositions that are curable with the Michael addition reaction; that cure at room temperature; that are two-pack compositions; and that eliminate the use of catalysts that are undesirably toxic, corrosive and/or undesirably reactive.
Accordingly, the invention provides a functional composition comprising:                (i) a first pack comprising at least one multi-functional Michael acceptor;        (ii) a second pack comprising at least one multi-functional Michael donor;        (iii) optionally, one or more non-functional ingredients;wherein at least one of said first pack and said second pack further comprises at least one weakly basic catalyst; wherein said first pack and said second pack are each storage-stable; and wherein a functional mixture formed by admixing ingredients comprising said first pack, said second pack, and is capable of curing at 23° C. in 7 days or less.        
The present invention also provides a functional composition comprising:                (i) a first pack comprising at least one multi-functional Michael acceptor;        (ii) a second pack comprising at least one multi-functional Michael donor;        (iii) optionally, one or more non-functional ingredients;wherein at least one of said first pack and said second pack further comprises at least one weakly basic non-amine, non-phosphine catalyst; wherein said first pack and said second pack are each storage-stable; and wherein a functional mixture formed by admixing ingredients comprising said first pack, said second pack, and is capable of curing at 23° C. in 7 days or less.        
The present invention also provides a functional composition comprising:                (i) a first pack comprising at least one multi-functional Michael acceptor;        (ii) a second pack comprising at least one multi-functional Michael donor;        (iii) optionally, one or more non-functional ingredients;wherein at least one of said first pack and said second pack further comprises at least one weakly basic catalyst; wherein said catalyst is selected from the group consisting of sodium salts of carboxylic acids, magnesium salts of carboxylic acids, aluminum salts of carboxylic acids, chromium salts of alkyl carboxylic acids that have 6 or fewer carbon atoms, chromium salts of aromatic carboxylic acids, potassium salts of alkyl mono-carboxylic acids that have 6 or fewer carbon atoms, potassium salts of multi-carboxylic acids, alkali metal carbonates, alkali metal bicarbonates, alkali metal phosphates, alkali metal hydrogen phosphates, alkali metal phosphate esters, and alkali metal pyrophosphates and mixtures thereof; wherein said first pack and said second pack are each storage-stable; wherein a functional mixture formed by admixing ingredients comprising said first pack, said second pack, and said optional non-functional ingredients is capable of curing at 23° C. in 7 days or less.        